The fascinating story of how Cornell plant breeder Michael Mazourek created the shrunken butternut squash you've been seeing all over the farmers' market.

At first glance, Honeynut squash just looks like a shrunken butternut squash. But it's more than that—the sweet, petite squash has only been in existence for less than a decade and didn't show up in farmers' markets until two years ago. Now its being grown at 90 percent of Northeast squash farms, with no signs of slowing down.

Honeynuts wouldn’t exist without a confrontation. In 2009, Jack Algiere, Stone Barns Center’s farm director, invited a group of plant breeders from Cornell University to have Chef Dan Barber cook for them at Blue Hill at Stone Barns in Pocantico Hills, New York. After the meal, Barber took breeder Michael Mazourek for a kitchen tour, grabbed a butternut squash and said: “If you’re such a good breeder, why don’t you make this thing taste good? Why don’t you shrink the thing?!”

It was kismet, because Mazourek, an associate professor in Plant Breeding and Genetics at Cornell, had been working on a mini squash for about a year—but he wasn’t getting a lot of interest from seed companies. “Minis had been a really hard sell because they don’t fit a lot of people’s concepts of what a good squash should be. For a lot of vegetables, runty is bad,” Mazourek explained. “I brought a farmer into our diagnostic lab and their first question was, ‘Why is it so small?’ People have conceptions and refrigerator magnet ideas of what a vegetable should look like, and they don't think you should pay more for something smaller.”

Photo by Emily Rodekohr

Honeynuts growing in a field at Cornell University.

The process to create a new vegetable can take years and up to eight generations of growing. Mazourek started by breeding two types of squash seeds together that had complementary characteristics. After those squash were harvested, he took seeds from that generation of squash and planted them. This "grandchildren generation" is when he started selecting the best of the best squash and collecting the highest quality seeds. As more generations grew, there was more uniformity in the squashes’ size, color, and texture. From there, Mazourek was able to to select the best possible Honeynut and grow more squash that were just like it. “This is something that would have taken our grandparents a lifetime to create. It took him just a couple of years,” Barber said.

Typically plants are bred for yield rather than flavor, but that changed with the Honeynut. Mazourek had Barber cook and taste-test frontrunners, and they narrowed down contenders based on flavor first and foremost. The way Barber cooked the Honeynuts was eye-opening to Mazourek—before, he and other breeders microwaved or steamed big batches of squash at low heat in a casserole pan with water, adding moisture and diluting flavor. (This was how all new breeds of vegetables were cooked for testing at Cornell.) Barber dry-roasted them at high heat, caramelizing the interior so it didn’t need brown sugar, maple syrup, or anything other than the squash’s natural sweetness. “Once we roasted them, that’s when the Honeynut really emerged—I realized how technique affected final flavor, and then we bred to achieve that,” Mazourek said.

Michael Mazourek

Mazourek and his team at Cornell use a repurposed Beemster double-handed cheese knife to slice into squash for sampling.

The final product is the Honeynut you can find primarily in the Northeast and at various farmers' markets and grocery stores across the country. They are stout, about 6" tall, and look almost exactly like a butternut squash was shrank in a Honey, I Shrunk the Kids-style machine. But the flavor is much more concentrated because their flavor isn't diluted from water weight. Honeynuts have an intense natural sweetness that becomes rich, caramel-y, and almost malt-like when roasted at high heat, they don't have to be peeled because they have thin skin (similar to a delicata), and they have have three times the amount of beta-carotene packed in. Mazourek described Honeynuts as “starchy with a smooth, even texture, and a flavor that gets sweeter as you eat it.” Its exterior is a deep honey color, and that—in addition to its inherent sweetness—is why it was named Honeynut.

In spite of all of these favorable characteristics, Mazourek had to jump through a few hurdles to get it to a wide audience. “Breeders like me have to convince a seed company to make a seed available, but they won’t do that if they don’t think growers are going to like it,” Mazourek said. (Seed companies license the Honeynut from Cornell, and share proceeds to help the university breed more new vegetables.) “Growers won’t grow it unless they see a retailer that is going to buy it, and a retailer is not going to make room for it if they don’t think there is a customer that will buy it. One of our setbacks was that retailers claimed they didn’t have a box to fit them, instead of just putting a bunch of Honeynuts into a butternut box.”

Mazourek credits the Honeynut’s rapid success to Barber introducing it to chefs at the G9 Chef’s Summit, an annual conference where nine of the world's top chefs meet and discuss food issues. In 2013, René Redzepi and Massimo Bottura were among the chefs who fell in love with the small squash, and Mazourek explained that “because there was a lot of clamoring for it, it ran away with itself in a really wonderful, surprising way—we could skip the line and move through the process faster than normal.” It took about two and half years to get it to market, whereas the squash he’s currently working on, a Honeynut 2.0 called the “898” that will hopefully have an extended seasonality and stay fresher longer, which he doesn’t expect to have a completed variety of for at least five years.

Chef Bill Telepan, who attended Barber’s conference that year, is now the executive chef at the seafood restaurant Oceana and uses Honeynuts in a seasonal vegetarian dish, simply roasting the squash in butter and vegetable stock and serving with sweet potato and spaghetti squash hash, delicata squash pieces, and mushroom purée. But he would eat it alone, too. “Squash can taste dead inside, but Honeynut is immediately vibrant and flavorful. You could eat it like a steak if you wanted to!” he raved. “The nutrients and natural sweetness make it great to give to kids, and it’s a good size for one—a single-serve squash.”

Whether it’s farmers, chefs, or food enthusiasts talking about it, it’s clear that word of mouth is what boosted the popularity of the Honeynut. Two years ago, half the farms in the Northeast that grew squash had it, Mazourek revealed. “Now 90 percent of the farms grow it—you see it moving beyond regional to Cleveland going west and Virginia going south,” he added. They are planted in May and harvest in late September or early October, and will be available through Christmas. If you’re trying to find the best Honeynut at the market, go for the one with the least green. They are green until they ripen, and are picked as soon as they turn a deep honey color. You can store them for a few months, but if they start to get wrinkly, that means it's drying out and you should use it ASAP.

Now you can get it at most Whole Foods, Costco, and meal kits—Barber said that Blue Apron bought 1.89 million pounds in 2017—even though most people hadn't heard of it three or four years ago. “It’s so successful because you don’t have to do anything to it and it tastes good,” Barber said. “The marketplace is shifting to breeding for flavor, chefs have a say in what’s growing, and Honeynut is the light at the end of the tunnel.”